I researched this and found a good thread but my situation is a little different. My propane tanks are near full, the water heater and stove work fine. I'm getting my power from an RV park and I see no problems with power elsewhere. IF I turn the heat off at the thermostat for a few minutes it will come back on for 5 to 10 minutes, but then quits. It's 55 degrees in the trailer. thermostat is set at 75.I tried the trick where you disconnect power to the furnace by pulling each fuse one at a time (of course they are not marked).The furnace is a Suburban Dynatrail.Where do I start to try and figure out the problem? I can't get to a shop for more than a week without causing a lot of trouble with my work.BTW it has been 2 years since the furnace was in the shop for a checkup. But the trailer has only been used once for a few days since then.

Almost sounds like a dirty fan sail switch. Locate it and spray all around it with WD-40. I always run the stove top for a few minutes to bleed off any possible air in the propane lines before using the furnace. Also a low battery might cause this as well but since you are on shore power I guess eliminates that being the problem. The thermostat runs on DC...just a couple of thoughts from here...Roy Ken

If not the sail switch or low battery it could be one of those overtemp buttons tripping. Check them with an ohm meter when it happens if you get no reading it is tripping. If near zero it is good.

Thank you for the replies. I located a manual online and it describes the sail switch as being on the fan housing. The installation instructions that came with the trailer shows a microswitch in the same spot. That's gotta be it. When the sun gets up I'll pull the cover off the furnace to see what I can do. I've never had that cover off, so this will be a good exercise.

I have the covers off of the furnace on both sides. There is nothing on either side that looks like a fan and sail switch. But when I pulled the cover off from that is accessible from inside the trailer I smell the low fuel smell. I did have a tank get low this week, but I switched to the full tank as soon as I recognized that odor. I'm not sure why the odor is still lingering till.Also, I switched the fridge to gas only and it's working fine.So, how do I find the sail switch? And, are there any other suggestions?

The key is the working of the furnace for a period of time. That makes me think that it is going into lockout in which you must break the thermostat call for heat (see excerpt from manual below) or possibly the over temp switch. The furnace may not be actually be getting overtemp, the switch may by weak and breaking at normal operating temp. If the sail switch was bad I would expect the furnace not to heat at all. The propane should not come on until after the sail switch makes. If no intervening act the switch. most likely will not move so furnace will continue to run.From suburban manual"All DYNATRAIL direct ignition furnaces must have a flame sensing circuit through the control module that senses the presence of main burner flame. If proper flame sensing is not obtained or if the burner fails to light, the furnace must go into 100% lockout. When lockout occurs, the valve closes and will remain closed until the thermostat circuit is broken. Re-ignition will not occur automatically. If it could, it would not be 100% lockout.While 100% lockout is a safety factor, it can prove to be frustrating for the RV owner who has experienced lockout problems. Not only can a lockout problem be difficult at times to diagnose, it will result in continuous operation of the furnace blower (that is, until the thermostat circuit is broken) and can drain the battery if the owner is not in the recreational vehicle.

Furnace runs, then quits, propane full, shore power

15 Replies

duggram
Explorer
Oct 07, 2013
wa8yxm wrote:
...it would start normally, the blower came on, a few seconds later the burner ignighted, things started warming up and then it shut down.

That's exactly what is happening with my furnace.

This morning about 2 hours before my normal wake up time, I got up to turn on my little area heater. I also turned on the furnace too and went back to sleep. When I woke up it was still working and kept working until the sun was up enough to warmup the trailer.

I'm still going to get it in the shop to figure this out next week when I get back to town.
wa8yxm
Explorer III
Oct 07, 2013
You say it runs for five minutes, Do you mean the blower blows or the burner burns?

I have had a problem with my Attwood where it would start normally, the blower came on, a few seconds later the burner ignighted, things started warming up and then it shut down.

Turns out I had a bad control board (Replaced with a Dinosaur board and all is fine now) but a bad thermocouple in the burner housing or a bad connection between the two can do that too.

The board was failing to read the signal (0.480 volts) from the flame sensor (Thermocouple) and thought ignition had not occurred.

I think I know why this happens.. It appears to folks at Dinosaur boards agree with me as they protected against this specific failure. But hey... IT works now.
kampinguru
Explorer
Oct 07, 2013
Are you actually getting heat out of the furnace when it runs or is it just blowing cold air? If it is just cold air, it could be spider webs in the orifice or it could be something has built a nest inside the furnace. I had a Finch nest built on top of the jet area of the furnace and we could only see it when we pulled the furnace.
nevadanick
Explorer
Oct 06, 2013
Is it forced air or a wall furnace ?
darsben
Explorer II
Oct 06, 2013
old guy wrote:
sounds like it is time for a call to a technician for repairs.

Actually depending on the model some of the troubleshooting procedures are relatively simple
old_guy
Explorer
Oct 06, 2013
sounds like it is time for a call to a technician for repairs.
darsben
Explorer II
Oct 06, 2013
duggram wrote:
darsben wrote:
... must break the thermostat call for heat (see excerpt from manual below)...

Exactly how do you do that? I tried turning off the power to the trailer and disconnecting the battery. That didn't work. The furnace starts, puts out heat for about 10 minutes and then shuts down. The thermostat is set for 75 and the room temp is 70.

What that means is if you break the call for heat at the thermostat then the unit resets. You still have the underlying problem and it will happen again. The owners manual gives troubleshooting tips for this problem.
I cannot guide you further as I do not have the exact model you are dealing with but it usually means either dirty orfices or LP gas problem.

Check the manual
duggram
Explorer
Oct 06, 2013
nevadanick wrote:
The sail switch is inside the squirell cage. Its activated when the cage is blowing air which is why its inside there. I hadto change mine early this year.

Hmmm.... I don't see anything that looks like a squirrel cage. On either end. Inside the trailer it looks like some kind of black manifold. Nothing like a blower or squirrel cage, I do know what that looks like.
duggram
Explorer
Oct 06, 2013
darsben wrote:
... must break the thermostat call for heat (see excerpt from manual below)...

Exactly how do you do that? I tried turning off the power to the trailer and disconnecting the battery. That didn't work. The furnace starts, puts out heat for about 10 minutes and then shuts down. The thermostat is set for 75 and the room temp is 70.
nevadanick
Explorer
Oct 06, 2013
The sail switch is inside the squirell cage. Its activated when the cage is blowing air which is why its inside there. I hadto change mine early this year.

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Furnace runs, then quits, propane full, shore power

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